JPS6313638B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a speaker voice coil with excellent heat resistance. Conventional voice coils for speakers are manufactured by using an insulating layer of polyester resin or urethane resin, and winding a magnet wire around a bobbin material with an adhesive layer of polyamide resin on the insulating layer. was. However, with the recent demand for higher input power from speakers, voice coils with excellent heat resistance are required, and voice coils using phenolic resin or epoxy resin as an adhesive layer, voice coils using imide resin, etc. Although various proposals have been made, each has problems in terms of heat resistance and workability, making mass production difficult. For example, epoxy resins with excellent adhesive properties have a heat resistance of around 200°C, while phenolic resins with excellent heat resistance tend to have extremely poor adhesive strength at temperatures above 200°C. Although it has been proposed to use a resin that has both of these characteristics, good results have not been obtained in terms of workability and other physical properties. Furthermore, since imide-based varnishes with excellent heat resistance require the use of high-boiling point solvents, workability has been hindered. In other words, when winding a magnet wire with an adhesive layer of amide-imide varnish around a bobbin material, the solvent contained in the varnish is a high boiling point solvent such as N-methylpyrrolidone, so it is difficult to volatilize and there is no initial adhesive strength. The problem was that it caused the magnet wire to come apart during winding, and since high boiling point solvents lack moisture resistance, the varnish tends to foam due to the moisture absorbed during curing by heating, causing deterioration of physical properties. . The present invention eliminates the above-mentioned conventional drawbacks, and aims to provide a voice coil for a speaker that has excellent heat resistance, stable quality, and excellent productivity. In order to achieve the above object, the present invention is characterized in that a resin containing bismaleimide resin and triazine resin as main components is used as an adhesive layer for the magnet wire and the bobbin material. Embodiments of the present invention will be described below with reference to FIGS. 1 to 3 of the drawings. Reference numeral 1 denotes a bobbin material made of metal foil or heat-resistant resin film. This bobbin material 1 is formed into a cylindrical shape, and the winding portion of this bobbin material 1 is coated with an adhesive layer mainly composed of bismaleimide triazine resin. 2
In this winding part, an insulating layer 4 made of polyester or urethane resin is provided around the outer periphery of a conductor 3 made of copper or aluminum, and an adhesive mainly composed of bismaleimide or triazine resin is provided around the outer periphery of this insulating layer 4. A magnet wire 6 having a layer 5 is wound thereon, and a reinforcing sheet 7 is wound around the portion other than this winding portion. The adhesives 2 and 5 mainly composed of bismaleimide/triazine resin are soluble in low boiling point solvents such as ketone solvents, so they are easy to work with when winding the magnet wire 6, and are extremely stable against moisture. Drying after winding is easy, there is no residual solvent, and there is almost no foaming due to heat curing. This eliminates deterioration of physical properties and adhesion. Note that this adhesive mainly composed of bismaleimide/triazine resin is made up of additives such as silicone resin and epoxy resin. When the adhesives 2 and 5 are cured, they form triazine rings, triazine imidazole rings, etc., and become thermally stable resins. The cured state is shown below. By bringing the adhesive layers 2 and 5 into a semi-cured state, better adhesion, heat resistance, and workability can be achieved. That is, an adhesive is applied to the bobbin material 1 to make it semi-hardened, and then a magnet wire 6 having a semi-hardened adhesive layer 5 is coated with a diluted varnish of bismaleimide triazine resin using methyl ethyl ketone as a solvent. While coating, wind the magnet wire 6 around the bobbin material 1, and after drying at room temperature,
Heat cure at a temperature of about 120℃ for 60 to 90 minutes. It is then completely cured at a temperature of 250-300°C for 60-90 minutes. or zinc octylate 0.02-0.05 as catalyst
% and 0.1 to 0.2% of dixyl peroxide and cured at 200 to 250°C. When hardening, use a cylindrical aluminum jig to prevent deformation. Aluminum jigs and tools have a large coefficient of thermal expansion, so in a voice coil wound with magnet wire 6 made of copper, which has a smaller coefficient of expansion than aluminum, the winding section can be pressurized from inside by the thermal expansion of the jigs and tools. Therefore, the adhesion between the magnet wire 6 and the bobbin material 1 and the adhesion between the magnet wires 6 can be performed more firmly. Next, an example will be described in which a voice coil constructed using bismaleimide triazine resin BT2420 (manufactured by Mitsubishi Kosikagaku Co., Ltd.) as an adhesive is compared with a conventional example. [Adhesion (using torque meter)] The adhesion performance of magnet wires obtained from a diameter of 0.1 mm was compared.

[Speaker input resistance]

A magnet wire with a diameter of 0.1 mm is used as a voice coil, and this voice coil is incorporated into a 25 cm diameter speaker with an 8 Ω impedance and used as a load.
Step up in 10W increments and load 3 at each load.
The input was maintained for several minutes and the input was compared until the voice coil was disconnected or an abnormal sound occurred.

【table】

[Table] In the conventional voice coil, the problem was caused by the magnet wire coming loose due to melting of the varnish, while in the present invention, the problem was caused by shorting due to carbonization of the adhesive. As the speaker voice coil of the present invention is constructed as described above, it is easy to manufacture, extremely stable against moisture, does not foam during curing, has excellent physical properties and adhesive properties, and has high input resistance. It has the advantage of being measurable and has great industrial value.

[Brief explanation of the drawing]

FIG. 1 is a half-sectional front view showing an embodiment of the voice coil for a speaker according to the present invention, FIG. 2 is an enlarged sectional view of the main parts of the voice coil, and FIG. FIG. DESCRIPTION OF SYMBOLS 1... Bobbin material, 2... Adhesive layer, 3... Conductor, 4... Insulating layer, 5... Adhesive layer, 6... Magnet wire, 7...
Reinforcement sheet.

Claims (1)

[Claims] 1. A voice coil for a speaker characterized in that an adhesive mainly composed of bismaleimide resin and triazine resin is used as an adhesive layer on the winding part of a bobbin material or the magnet wire wound around this winding part. .